ON VARIATION. 45 



body. In the C. tessellatus rubidus the dark spots dis- 

 appear first on the anterior regions. 



According to Eimer,i among many color-variations 

 of the Lacerta muralis there exists a series of types 

 closely similar to those observed by me to characterize 

 the two species of Cnemidophorus mentioned. I give 

 figures of these series in all three species. It will be 

 observed that in the second and third forms (B and C) 

 of the L. muralis, the pale portions of the dark stripes 

 do not assume the very light hue of the ground color 

 as they do in the corresponding phase of the Cnemido- 

 phorus tessellatus (C and D, Fig. 12), but this interme- 

 diate condition is exactly paralleled by the subspecies 

 ' mariarum of the Cnemidophorus gularis. The corre- 

 spondences are represented in the table on page 46. 



There are some color forms in the Lacerta muralis 

 which are not repeated in the North American Cnemi- 

 dophori, particularly those which result in a strong 

 contrast between the dorsal colors as a whole and the 

 darker lateral colors, as a band. The color variety,- 

 No. 7, of the Cnemidophori is not reported by Eimer 

 as occurring in the Lacerta muralis. 



The variations from one to four form a direct series, 

 and so do those represented by Nos. i, 2, 3, and 5. 

 Such variations cannot be regarded as promiscuous, 

 especially when the same process of change is to be 

 observed in three different species, one of which in- 

 habits a continent remote from the other two. 



d. Variations in North American Birds: and Mammals in 

 Relation to Locality. 



The distinguished zoologist, Dr. J. A. Allen of New 

 York, has made a thorough study of this subject with 



\ArckivfUr Naturgeschichte, 1881, p. 239. 



